This invention relates to a silent or inverted tooth chain for transmitting power in an automobile, motorcycle or other vehicle. More specifically, this invention relates to a power transmission chain having a large number of interleaved links. The links are arranged in rows or sets and connected by connecting pins. Guide links are located at the outermost sides of alternate sets of links. Spring links are included in some rows or sets of links.
In conventional silent chains used as a power transmission chain for automobiles and motorcycles, spring links are typically used for reduction of chordal vibration of the chain and reduction of the chain noise. An example of a conventional chain of the prior art is shown in FIGS. 4 and 5. In this chain, a large number of inverted tooth links or link plates 51 are interleaved in rows by connecting pins 52. Guide links or guide plates 53 are located at the outermost sides of alternate sets of links. The inverted tooth links are constructed and arranged to articulate with respect to one another, and transmit power, as the chain passes over the sprockets. The guide links act to maintain the chain on the sprockets.
Additionally, spring link 54 is located or sandwiched between one guide plate 53 and its adjacent link plate 51. Spring link 54 has one pair of apertures or pinholes 54a for insertion of connecting pins, as shown in FIG. 5, and its center portion is pressed against the guide plate 53 while both of its ends are pressed against the link plate 51. As the links move around the sprockets and articulate with respect to one another, friction occurs between adjacent link plates 51 and the bending resistance of the chain is increased because of the elastic repulsive force of this spring link 54. As a result, the chordal vibration of the chain is reduced or suppressed.
In this conventional silent chain, the guide plate contacting parts at both ends of spring link 54 contact the edge of aperture 54a, as shown in the cross-hatched part D of FIG. 5(a) and the circled location D' of FIG. 5(b). Therefore, the aperture or pinhole edge that intersects the cross-hatched part D tends to become the point of origin of fatigue, which decreases the durability of the spring link.
Other examples of power transmission chains with spring links are found in U.S. Pat. No. 5,090,948 (particularly FIG. 16), U.S. Pat. No. 5,167,587 (particularly FIG. 16), and U.S. Pat. No. 5,007,883 (particularly FIGS. 14-16), each of which is incorporated herein by reference.
The present invention is directed to the above-described problems in the conventional chains, and offers a power transmission chain that further improves the durability of the spring link.